I totally agree! It doesn't matter how amazing your product is if no one ever lays eyes on it or is compelled to give it a try. I actually spent a not insignificant amount of time during and after the jam making my game as appealing as possible. I found some things that may help grab attention:
Art: Although game jams are not about the art, we are humans and are inevitably drawn to look at pretty things.
Thumbnail: It should look nice, be simple, and give a hint to the gameplay to come.
Title: A catchy sharable title goes a long way to help communicate your product and increases it's sharability.
That's what I got so far.